The present invention generally relates to tape cassette loading and unloading apparatuses, and more particularly to a tape cassette loading and unloading apparatus provided in a magnetic recording and/or reproducing apparatus and having a holder which is inserted with a tape cassette, a belt-driven transmitting mechanism for moving the holder between a cassette receiving position and a predetermined loading position, and a lock mechanism for locking the transmitting mechanism when the holder reaches the predetermined loading position.
Conventionally, a tape cassette loading and unloading apparatus provided in a magnetic recording and/or reproducing apparatus comprises a holder for receiving a tape cassette which is inserted into the recording and/or reproducing apparatus. The holder is movable between a cassette receiving position where an inserted tape cassette is received and a predetermined loading position where a recording or a reproduction is carried out with respect to a magnetic tape accommodated within the tape cassette. The holder is moved by a rotational driving force of a drive motor transmitted by way of a worm gear coupled to a rotary shaft of the drive motor and a transmitting mechanism coupled to the worm gear and the holder. The worm gear comprises a worm and a worm wheel which meshes with the worm. When the drive motor is stopped at a time when the holder reaches the predetermined loading position during a loading mode or when the holder reaches the cassette receiving position during an unloading mode, a force acts on the holder so as to rotate the worm wheel or rotate toothed wheels of the transmitting mechanism. However, due to the meshing relationship between the worm and the worm wheel which meshes with the worm, the worm wheel does not rotate and the holder is locked in the predetermined loading position or the cassette receiving position. Accordingly, the worm gear also functions as a lock mechanism for locking the holder in the predetermined loading position or the cassette receiving position.
But when the holder is stopped, a load acts on the worm gear. The load acting on the worm wheel or the worm is large and may damage the worm gear. Hence, it is necessary to provide a resilient member in the transmitting mechanism and resiliently absorb the movement in the transmitting mechanism when the holder stops in the predetermined loading position or the cassette receiving position, in order to reduce the load acting on the worm gear when the holder stops. As a result, the construction of the tape cassette loading and unloading apparatus becomes complex.
Accordingly, in a conceivable tape cassette loading and unloading apparatus, it is possible to provide a pulley on the rotary shaft of the drive motor instead of providing the worm gear. In this case, the holder is moved by the rotational driving force of the drive motor which is transmitted by way of the pulley, a belt provided between the pulley and the transmitting mechanism, and the transmitting mechanism. When the holder stops in the predetermined loading position or the cassette receiving position, the belt slips and it is possible to prevent an excessively large load from being applied on the transmitting mechanism.
However, in the case of the holder which is moved by way of the belt-driven transmitting mechanism, the holder in the predetermined loading position may be moved by an external force which acts on the holder. That is, when an external vibration or shock is applied on the holder in the predetermined loading position, the toothed wheels of the transmitting mechanism may rotate and hence rotate the pulley and the drive motor by way of the belt. As a result, there is a problem in that the holder may move from the predetermined loading position and make it impossible to carry out the recording or reproduction on the recording and/or reproducing apparatus.
Moreover, in the case of the holder which is moved by way of the belt-driven transmitting mechanism, it is possible to conceive a construction in which the holder is moved to the predetermined loading position by a rotary member which is driven by the drive motor, the rotary member rotates further against a resilient member when the holder reaches the predetermined loading position so as to push against and keep the holder in the predetermined loading position by an urging force of the resilient member, and the rotary member is locked in this state by a locking member. However, according to this conceivable construction, the load on the rotary member is large because the rotary member moves the holder to the predetermined loading position by the rotary displacement thereof, the rotary member pushes and keeps the holder in the predetermined loading position via the resilient member, and the rotary member is locked by the locking member in the state where the rotary member is rotated against the urging force of the resilient member. In addition, the drive motor must have a large driving force in order to push the holder to the predetermined loading position by the rotary member against the urging force of the resilient member, and there is a problem in that the the drive motor becomes bulky. Furthermore, there is a problem in that the lock member must be provided in addition to a reduction gear mechanism which drives the rotary member.